Deployment system for an endoluminal device

ABSTRACT

The present invention is directed to a deployment system for an endoluminal device. The deployment system includes a confining sheath placed around a compacted endoluminal device. A deployment line is provided in the system that is an integral extension of the sheath. As the deployment line is actuated, the sheath retracts from around the compacted endoluminal device. As the sheath retracts from around the endoluminal device, material from the sheath may be converted into deployment line. Once the sheath is retracted from around the compacted endoluminal device, the endoluminal device expands in configuration and repairs vascular or cardiac structures of an implant recipient. Any remaining sheath material is removed from the implantation site along with the deployment line.

FIELD OF THE INVENTION

The present invention relates generally to implantable medical deviceassemblies. In particular, the invention relates to means for deployingan endoluminal device within vascular or cardiac structures of animplant recipient.

BACKGROUND OF THE INVENTION

Various implantable medical devices for repairing or reinforcing cardiacand vascular structures have been developed in recent years. Some ofthese devices can be implanted inside a particular vascular or cardiacstructure through so-called interventional, or endovascular, techniques.Interventional techniques involve surgically accessing the vascularsystem through a conveniently located artery or vein and introducingdistal portions of a medical device assembly into the vascular systemthrough the arterial or venous access point. Once the medical deviceassembly is introduced into the vascular system, it is threaded throughthe vasculature to an implantation site while proximal portions of theassembly having manually operated control means remain outside the bodyof the implant recipient. The medical device component of the assemblyis then deposited at the implantation site and the remainder of thedistal portion of the medical device assembly removed from the vascularsystem through the access point.

Exemplary interventional medical device assemblies include a catheter.The catheter can be used to precisely position the medical device at animplantation site as well as participate in deployment of the medicaldevice at the implantation site. Some catheters have guidewires runningtheir length to aid in positioning and deployment of the medical device.As an alternative to the guidewire, a catheter may be coaxial with aninner sleeve running inside the length of the catheter. The inner sleeveis used to hold an implantable medical device in position while theouter catheter is pulled, causing deployment of the device. Handles,knobs, or other manually operated control means are attached to theopposite end of the catheter in this assembly.

Some implantable medical devices, such as stents, stent-grafts, or otherendoluminal devices often require reconfiguration from an initialcompacted form to an expanded cylindrical configuration as the device isdeployed at an implantation site. These devices can expand on their ownby virtue of the design and composition of their structural elements orthrough the use of an inflatable balloon placed inside the devices.

Self-expanding endoluminal medical devices are maintained in a compactedconfiguration in a variety of ways. Some devices are maintained in acompacted configuration by simply confining the compacted devices insidea catheter, or similar tool. Other devices are placed inside a sheathfollowing compaction. In these assemblies, a control line is often usedto assist in releasing the endoluminal device from the sheath.

In U.S. Pat. No. 6,352,561, issued to Leopold et al., a sheath is formedaround an expandable endoluminal device and a control line used tomaintain the sheath around the endoluminal device. The sheath is formedby folding a length of polymeric material in half and stitching theopposing edges together with the control line. The stitching patternpermits the control line to be removed from the sheath by pulling on aproximal end of the control line. As the control line becomes unstitchedfrom the sheath, the endoluminal device is progressively released fromconfinement within the sheath. The control line is removed from theassembly as a distinct entity while the sheath remains at theimplantation site.

In U.S. Pat. No. 5,647,857, issued to Anderson et al., an endoluminaldevice is held in a collapsed configuration over a catheter by a sheath.The assembly is provided with a control line having a free end and anend attached to a collar component of the catheter. The sheath isremoved from the endoluminal device by pulling on the control line. Asthe control line is pulled, it cuts through and splits the sheathmaterial from distal end to proximal end. As the sheath splits open, theendoluminal device is freed to expand. Unlike Leopold et al., thecontrol line remains mechanically attached to the sheath and catheterassembly following deployment of the endoluminal device.

In U.S. Pat. No. 6,447,540, issued to Fontaine et al., a confiningsheath is removed from around an endoluminal device with a control linethat cuts through and splits the sheath material when pulled by apractitioner, much like Anderson et al. As with Leopold et al, thecontrol line can be completely removed from the assembly as a distinctentity.

In U.S. Pat. No. 5,534,007, issued to St. Germain et al., asingle-walled sheath that can collapse and shorten along its length isplaced around a stent. As the distal portion of the sheath is retracted,it uncovers the stent. The uncovered stent is free to expand. A controlline can be used to exert a pulling force on the collapsible sheath as ameans of removing the sheath from the stent. The control line remainsattached to the sheath during and subsequent to deployment of the stent.

In U.S. Pat. No. 6,059,813, issued to Vrba et al, a double-walledconfinement sheath for an endoluminal device is described. In anassembly made of these components, the endoluminal device is placed overa catheter shaft in a collapsed configuration. An outer tube is placedin slidable relationship over the catheter. The distal end of the outertube does not extend to cover the endoluminal device. Rather, the doublewalled sheath is placed over the collapsed endoluminal device. The innerwall of the sheath is attached to the catheter shaft near the proximalend of the endoluminal device. The outer wall of the double-walledsheath is mechanically attached to the outer tube. Movement of the outertube relative to the catheter causes the outer wall of the sheath tomove past the inner wall of the sheath. Movement of the outer tube inthe proximal direction causes the sheath to retract and uncover theunderlying endoluminal device. As the sheath retracts, the endoluminaldevice becomes free to expand. A control line is mechanically attachedto the outer tube and serves to move the outer tube and retract thesheath.

None of these medical device assemblies utilize a control line that isintegral with a confining sheath. Nor do these assemblies feature asheath that is convertible to a control line as the sheath is removedfrom around the endoluminal device. Such an integral control line andconfining sheath would preferably be made of a continuous thin-walledmaterial or composite thereof. The thin-walled material would beflexible and exert minimal restrictions on the flexibility of anunderlying endoluminal device. Thin-walled materials would also reducethe profile of the sheath and endoluminal device combination. Anintegral control line and confining sheath would simplify manufacture ofcontrol line—sheath constructs by eliminating the need to mechanicallyattach the control line to the sheath. An integral control line andconfining sheath would also eliminate concerns regarding the reliabilityof the mechanical attachment of the control line to the sheath.

SUMMARY OF THE INVENTION

The present invention is directed to a deployment system for anexpandable endoluminal device. In preferred embodiments, the endoluminaldevice is self-expanding as a consequence of the device design and thematerials used to construct the device. In other embodiments, theendoluminal device is expanded with an inflatable balloon placed withinthe device. The endoluminal device is maintained in a compacted, orcollapsed, configuration by a removable sheath. The sheath is removedfrom around the endoluminal device by pulling on a deployment line. Thedeployment line is an integral, continuous, extension of the sheath thatis made of the same material as the sheath. As the deployment line ispulled, the sheath progressively retracts from around the endoluminaldevice and also functions as an extension of the deployment line. Whenthe sheath has been substantially removed from around a portion of theendoluminal device, that portion of the endoluminal device is free toexpand. Removal of the sheath may be continued until the entireendoluminal device is freed from radial constraint. The deployment line,along with any remaining sheath material, may be removed from theimplantation site through the use of a catheter used to deliver thesheathed endoluminal device to the site.

The removable sheath is made of one or more thin, flexible polymericmaterials including composites thereof. The sheath ordinarily assumesthe form of a continuous thin-walled tube when constraining anendoluminal device. Such a thin-walled sheath exerts minimal resistanceto longitudinal flexing of an underlying endoluminal device. Thethin-walled sheath also reduces the profile of the sheath—endoluminaldevice combination, when compared to conventional constraints. Inpreferred embodiments, a double-walled tubular sheath is used. Doublewalls enable the sheath to be retracted from around an endoluminaldevice by rolling or sliding one wall past the other wall. As the sheathis retracted in this manner, the sheath portion does not rub or scrapagainst the endoluminal device. This is particularly advantageous whencoatings containing medications or pharmaceuticals are placed onsurfaces of the endoluminal device that may be removed by a sheath thatrubs or scrapes against the endoluminal device during removal.

The deployment line is formed from the same material as the tubularsheath and is an integral extension of the sheath material. Thedeployment line extends from the sheath through a delivery catheter to acontrol knob located at the proximal end of the catheter. Pulling on thecontrol knob actuates the deployment line. Once the deployment line isactuated, the removable sheath begins to retract from around theendoluminal device.

In one embodiment, as removed sheath material travels beyond thereceding end of the sheath, the sheath begins to become converted todeployment line. Conversion of the sheath into the deployment lineusually begins at a point where the tubular sheath breaks apart,separates, and converges into deployment line material. In preferredembodiments, means are provided for initiating or sustaining theconversion of the sheath to deployment line. These means may take theform of perforations, stress risers, or other mechanical weaknessesintroduced into the sheath material. The means can also be cutting edgesor sharp surfaces on the delivery catheter.

In preferred embodiments, materials and/or composites exhibitingcompliance, compressibility, and/or resilience are placed between theendoluminal device and the delivery catheter. The compliant materialserves to cushion the endoluminal device when constrained by the sheathand may assist in expansion of the device when unconstrained. Thecompliant material also serves to anchor and retain the endoluminaldevice in place on the underlying catheter shaft. When used incombination with a double-walled sheath, the compliant material can havetacky surfaces that further assist in anchoring and retaining theendoluminal device. In these embodiments, the tacky surface of thecompliant material do not interfere with removal of the sheath fromaround an endoluminal device. The anchoring of the endoluminal devicevia the compliant material eliminates the need for barrier, or retentionmeans at either end of the endoluminal device. The absence of barriermeans also contributes to a reduction in the profile and an increase inflexibility of the distal portion of the assembly. The present inventioncan also be provided with an additional catheter or catheter lumen forthe deployment line in order to prevent the deployment line from leavingthe general path established by the delivery catheter.

Accordingly, one embodiment of the present invention is a deploymentsystem for a self-expanding endoluminal device comprising a removablesheath adapted to cover the endoluminal device, the sheath comprising athin continuous film adapted to surround at least a portion of theendoluminal device and constrain the device in an introductory profile,wherein the deployment system includes a deployment line integral withthe sheath to effectuate device deployment, and wherein upon deployment,the sheath separates from the endoluminal device through actuation ofthe deployment line, the sheath becoming removed from the device alongwith the deployment line.

In another embodiment, the present invention is a deployment system fora self-expanding endoluminal device comprising a self-expandingendoluminal device at least partially enclosed by a removable sheath,and a deployment line integral with the sheath, wherein the sheath isconvertible to the deployment line as the sheath is removed from theendoluminal device.

These enhanced features and other attributes of the deployment system ofthe present invention are better understood through review of thefollowing specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a longitudinal cross-section of the presentinvention.

FIG. 1A is an enlarged view of FIG. 1.

FIG. 2 illustrates a perspective view of the present invention.

FIG. 3 illustrates a longitudinal cross-section of the presentinvention.

FIG. 3A is an enlarged view of FIG. 3.

FIG. 4 illustrates a longitudinal cross-section of the presentinvention.

FIG. 4A is an enlarged view of FIG. 4.

FIG. 5 illustrates a longitudinal cross-section of the presentinvention.

FIG. 5A is an enlarged view of FIG. 5.

FIG. 6 illustrates a longitudinal cross-section of the presentinvention.

FIG. 6A is an enlarged view of FIG. 6.

FIG. 7 illustrates a longitudinal cross-section of the presentinvention.

FIG. 7A is an enlarged view of FIG. 7.

FIG. 7B illustrates the embodiment of FIG. 7A as viewed from thedirection indicated by the arrow.

FIG. 7C illustrates the embodiment of FIG. 7A as viewed from thedirection indicated by the arrow.

FIGS. 8 and 8A illustrate longitudinal cross-sections views of thepresent invention placed inside a vascular or cardiac structure.

FIG. 9 illustrates a longitudinal cross-section of the present inventionwith a covering placed over a compressible material.

FIG. 9A illustrates a longitudinal cross-section of the presentinvention without a covering placed over a compressible material.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a deployment system for anexpandable endoluminal device having a removable distal tubular sheathwith a deployment line or filament that is an integral part of thesheath. The sheath radially confines the endoluminal device in acompacted or collapsed configuration during storage and introductioninto a patient's vascular system. The confining sheath maintains theendoluminal device in a compacted configuration until the device isdelivered with a catheter to an implantation site in a vascular orcardiac structure. As the deployment line is actuated, it pulls on thedistal tubular sheath and begins to retract the sheath from theendoluminal device. In some embodiments, sheath material may beconverted into deployment line material as the sheath is removed fromthe endoluminal device. As the distal tubular sheath is removed from theendoluminal device, the endoluminal device is free to expand. Once freefrom the confining sheath, the endoluminal device may expandspontaneously or with the assistance of an inflatable balloon. Anyremaining sheath material may be removed from the implantation sitealong with the deployment line.

The integral sheath—deployment line is preferably a flexible polymericmaterial that is continuous along the length of the construct.Preferably, the physical and mechanical properties of the sheath portionare such that they are uniform and homogeneous throughout the length ofthe sheath portion used to constrain the endoluminal device. Since mostendoluminal devices are generally circularly cylindrical in form, thesheath is preferably tubular in shape in order to enclose most or all ofthe endoluminal device. Conical, tapered, or other suitable shapes forthe sheath are also contemplated in the present invention. Flexibilityof the sheath is enhanced by making the walls of the sheath as thin aspracticable. In one embodiment of the present invention (20), thetubular sheath portion (12 a) of the sheath—deployment line has a singlewall (FIG. 3). The deployment line portion can extend from either end ofthe single-walled sheath (12 a). When the sheath portion is retractedfrom around an endoluminal device, the length of retracted sheath issubstantially equal to the length of deployment line displaced duringdeployment of the endoluminal device.

In another embodiment of the present invention (10), the sheath portion(12) of the Sheath—deployment line has a double wall (FIGS. 1-2). In apreferred embodiment, the double walled-sheath portion (12) is made of apolymeric material that is folded on itself. The double-walled sheathportion is placed over the endoluminal device so that the fold (22) ispositioned at the distal end of the sheath portion. The inner wall ofthe sheath portion may be anchored to part of an underlying deliverycatheter (19) proximal to the endoluminal device (14). In preferredembodiments, the sheath portion is not attached to the deliverycatheter. The proximal end of the outer wall of the sheath has at leastone portion, or integral extension, that is convertible to deploymentline (16). Space between the walls of the double-walled sheath portioncan be filled with fluids, lubricants, pharmaceutical compositions,and/or combinations thereof. The deployment line (16) is routed throughthe delivery catheter (19) to a control knob (not shown) located at thedistal end of the deployment system (10). Alternatively, a separatecatheter (13) or catheter lumen (11) is provided for the deployment line(FIGS. 4 and 1, respectively). These embodiments provide additionalcontainment of the deployment line portion, particularly when bends orcurves in a patient's vasculature having small radii are anticipated.Preferably, the physical and mechanical properties of the sheath portionare such that they are uniform and homogeneous throughout the length ofthe sheath portion used to constrain the endoluminal device. When thesheath portion is retracted from around an endoluminal device, thelength of retracted sheath is essentially half the length of deploymentline displaced during deployment of the endoluminal device. This two toone ratio of length of deployment line removed to length of sheathmaterial removed reduces the effect of too rapid or strong a pull on thedeployment line on release of the endoluminal device from the sheath.

Fluoropolymer materials are preferred for making the retractable tubularconstraining Sheath—deployment line constructs of the present invention.Fluoropolymer materials used in the present invention are strong, thin,and lubricious. The lubriciousness of the fluoropolymer materials isespecially advantageous in embodiments utilizing a sheath—deploymentline having walls that slide past one another or over an endoluminaldevice. Particularly preferred fluoropolymer materials are porousexpanded polytetrafluoroethylene materials alone or in combination withfluorinated ethylene propylene materials. Most preferred fluoropolymermaterials are strong and thin, such as those described in Example 2,infra. The sheath—deployment line is made by constructing an appropriatetube from layers of film and membrane. A significant portion of thistube is then rendered filamentous by rolling and heating.

The sheath may be converted to deployment line by pulling on thedeployment line and causing the sheath material to separate and convergeinto a single filament. As sheath material is converted to deploymentline by this process, the edge of the sheath supplying material to thedeployment line recedes causing the sheath to retract from around theendoluminal device. As a portion of the sheath retracts, the portion ofthe endoluminal device confined by the sheath is freed to expand (FIGS.8-8A). Means are optionally provided to the deployment system thatinitiate or sustain the conversion of sheath to deployment line. Asshown in FIG. 7, the means include perforations (71), cutouts (72), orother engineered defect introduced into the sheath material. As shown inFIG. 5, the means also include cutters (21) or other sharp edges on thedelivery catheter. Such cutting means may be formed on the deliverycatheter by exposing a strand of reinforcing stainless steel from withinthe catheter and adapting the strand to cut into the sheath portion.

In the preferred embodiment of the present invention, materials and/orcomposites exhibiting compliance, compressibility, and/or resilience areplaced between the delivery catheter and the endoluminal device.Preferably, the compliant material is also compressible. At least aportion of the endoluminal device is pressed into the compressiblematerial to anchor the endoluminal device on the delivery catheter andprevent the endoluminal device from moving along the length of thecatheter. Materials with a tacky surface are useful in this embodiment,particularly in combination with a lubricious sheath material. Thecompressible anchor material eliminates the need for barrier, orretention, means placed at the proximal and distal end of theendoluminal device. In addition to added flexibility imparted to thedeployment system without the barrier means, the profile of the sheathand endoluminal device combination is reduced without the barrier means.In the most preferred embodiment, the compressible material also hasresilience that assists in expanding the endoluminal device followingremoval of the confining sheath. Suitable materials for the compressiblematerial include, but are not limited to, silicones, silicone foams,polyurethane, polyurethane foams, and polytetrafluoroethylene foams. Thecompressible material is attached to the outer wall of the deliverycatheter with adhesives, heat, or other suitable means.

The compressible material is preferably enclosed with a polymericmaterial (15). The polymeric material is preferably afluoropolymer-based material. Porous expanded polytetrafluoroethylene isthe preferred fluoropolymer for enclosing the compressible material.Other suitable polymeric materials include, but are not limited to,silicone, polyurethane, and polyester.

EXAMPLES Example 1

This example describes the construction of a deployment system of thepresent invention. Construction of the system began with the preparationof a distal catheter shaft for receiving an expandable stent. Once thedistal catheter was prepared, the expandable stent was placed within asheath—deployment line. The distal catheter portion of this combinationwas attached to a primary catheter shaft. The deployment line portionwas then routed through the primary catheter to a control knob. Thecontrol knob was part of a hub located proximally on the primarycatheter. The sheath portion of the sheath—deployment line was in theform of a single-walled tube.

A tubular material three inches long was obtained from BurnhamPolymeric, Inc., Glens Falls, N.Y. for use as the distal catheter shaft.The tube was made of a polyether block amide material, commonly known asPEBAX® resin and reinforced with a stainless steel braid. The outerdiameter (OD) was 1.01 mm and the inner diameter (ID) was 0.76 mm. Acompressible material in the form of a cushion was then placed on thecatheter. To place the cushion on the catheter, the catheter was mountedon a mandrel having an outer diameter of 0.74 mm. A film of porousexpanded polytetrafluoroethylene (ePTFE) was obtained according to theteachings in U.S. Pat. No. 5,814,405, issued to Branca, which isincorporated herein by reference. A discontinuous coating of fluorinatedethylene propylene (FEP) was applied to one side of the ePTFE materialin accordance with U.S. Pat. No. 6,159,565, issued to Campbell et al.,and incorporated herein by reference. An edge of the ePTFE—FEP compositefilm two inches wide was attached with heat to the catheter shaft. Afterinitial attachment, the film was wrapped around the catheter shaftforty-five (45) times under light tension. With every fifth wrap of thefilm, and on the final layer, the film is further attached to itselfwith heat. This procedure provides a compressible material, or compliant“pillow,” on the distal catheter shaft. The expandable stent is mountedover the compressible material. The compressible material provides ameans of retaining an expandable stent on the catheter shaft duringstorage, delivery to an implantation site, and deployment of theexpandable stent at the implantation site. Optionally, the compressiblematerial may be reinforced with a thin coating of an elastomericmaterial such as silicone, urethane, and/or a fluoroelastomer.

An eight (8) cell, 6 mm diameter, nitinol stent was obtained fromMedinol Ltd., Tel-Aviv, Israel. The stent was placed over thecompressible material of the catheter in an expanded state. Thecombination was placed within a machine having a mechanical iris thatcompacts or compresses the stent portion of the assembly onto thecompressible material. While retained in the mechanical iris machine,the stent was reduced in temperature from room temperature toapproximately five degrees centigrade (5° C.). At the reducedtemperature, the iris machine was actuated to compact, or collapse, thestent onto the compressible material. While in the refrigerated andcompressed configuration, the catheter, compressible material, and stentwere placed within a sheath—deployment line of the present invention.

The sheath—deployment line having a length equal to, or greater than,the length of the final deployment system was made as follows. Astainless steel mandrel measuring 1.73 mm in diameter was covered with asacrificial layer of ePTFE. The sacrificial ePTFE material aids inremoval of the sheath—deployment line from the mandrel. Two wraps of athin polytetrafluoroethylene (PTFE) membrane were applied to themandrel. The ePTFE membrane was applied so the primary strength of thefilm was oriented parallel with the longitudinal axis of the mandrel.The membrane was initially tacked in place with heat applied with asoldering iron. The membrane thickness measured about 0.0002″ (0.005 mm)and had tensile strengths of about 49,000 psi (about 340 KPa) in a firstdirection and of about 17,000 psi (about 120 KPa) in a second direction(perpendicular to the first direction). The tensile measurements wereperformed at 200 mm/min. load rate with a 1″ (2.5 cm) jaw spacing. Themembrane had a density of about 2.14 g/cm³. This membrane was furthermodified by the application of an FEP coating on one side in accordancewith U.S. Pat. No. 6,159,565, issued to Campbell et al., which isincorporated herein by reference. Next, two wraps of the same ePTFEmembrane were applied to one end of the construction (approx. 1″ wide).These two wraps had the primary strength direction of the film orientedperpendicular to the mandrel's longitudinal axis. These layers of filmprovide additional “hoop” or “radial” strength to the sheath—deploymentline construct. The mandrel and sheath—deployment line construct wereplaced in an air convection oven obtained from The Grieve Corporation,Round Lake, Ill., and subjected to a thermal treatment of 320° C. for 12minutes. After air cooling, the ePTFE/FEP tube construct was removedfrom the mandrel and the sacrificial ePTFE layer removed. The constructwas then attached to a primary catheter shaft using heat and standardmaterials.

The deployment line portion of the sheath—deployment line was made bysplitting the sheath—deployment line along its length from a proximalend up to, but not including, the sheath portion enclosing the stent.The material thus obtained was gathered into a filament by rolling thematerial. Heat was applied to the material to set the material in thefilamentous form. The deployment line filament was routed through alumen in the primary catheter and connected to a control knob. Thecontrol knob was part of a hub located at the proximal end of theprimary catheter. When the deployment line portion of thesheath—deployment line was pulled, the sheath portion was retracted fromaround the stent.

Example 2

This example describes the construction of a deployment system of thepresent invention. Construction of the system begins with thepreparation of a distal catheter shaft for receiving an expandablestent. Once the distal catheter was prepared, the expandable stent wasplaced within a sheath—deployment line. The distal catheter portion ofthis combination was attached to a primary catheter shaft. Thedeployment line portion was then routed through the primary catheter toa control knob. The control knob was part of a hub located proximally onthe primary catheter. The sheath portion of the sheath—deployment linewas in the form of a double-walled tube.

A tubular material three inches long was obtained from BurnhamPolymeric, Inc., Glens Falls, N.Y. for use as the distal catheter shaft.The tube was made of a polyether block amide material, commonly known asPEBAX® resin and reinforced with a stainless steel braid. The outerdiameter (OD) was 1.01 mm and the inner diameter (ID) was 0.76 mm. Acompressible material in the form of a cushion was then placed on thecatheter. To place the cushion on the catheter, the catheter was mountedon a mandrel having an outer diameter of 0.74 mm. A film of porousexpanded polytetrafluoroethylene (ePTFE) was obtained according to theteachings in U.S. Pat. No. 5,814,405, issued to Branca, which isincorporated herein by reference. A discontinuous coating of fluorinatedethylene propylene (FEP) was applied to one side of the ePTFE materialin accordance with U.S. Pat. No. 6,159,565, issued to Campbell et al.,which is incorporated herein by reference. An edge of the ePTFE—FEPcomposite film two inches wide was attached with heat to the cathetershaft. After initial attachment, the film was wrapped around thecatheter shaft forty-five (45) times under light tension. With everyfifth wrap of the film, and on the final layer, the film is furtherattached to itself with heat. This procedure provides a compressiblematerial, or compliant “pillow,” on the distal catheter shaft. Theexpandable stent is mounted over the compressible material. Thecompressible material provides a means of retaining an expandable stenton the catheter shaft during storage, delivery to an implantation site,and deployment of the expandable stent at the implantation site.Optionally, the compressible material may be reinforced with a thincoating of an elastomeric material such as silicone, urethane, and/or afluoroelastomer.

An eight (8) cell, 6 mm diameter, nitinol stent was obtained fromMedinol Ltd., Tel-Aviv, Israel. The stent was placed over thecompressible material of the catheter in an expanded state. Thecombination was placed within a machine having a mechanical iris thatcompacts or compresses the stent portion of the assembly onto thecompressible material. While retained in the mechanical iris machine,the stent was reduced in temperature from room temperature toapproximately five degrees centigrade (5° C.). At the reducedtemperature, the iris machine was actuated to compact, or collapse, thestent onto the compressible material. While in the refrigerated,compressed configuration, the catheter, compressible material, and stentwere placed within a sheath—deployment line of the present invention.

The sheath—deployment line having a length equal to, or greater than,the length of the final deployment system was made as follows. Astainless steel mandrel measuring 1.73 mm in diameter was covered with asacrificial layer of ePTFE. The sacrificial ePTFE material aids inremoval of the sheath—deployment line from the mandrel. Two wraps of athin, polytetrafluoroethylene (PTFE) membrane were applied to themandrel. The ePTFE membrane was applied so the primary strength of thefilm was oriented parallel with the longitudinal axis of the mandrel.The film was initially tacked in place with heat applied with asoldering iron. The membrane thickness measured about 0.0002″ (0.005 mm)and had tensile strengths of about 49,000 psi (about 340 KPa) in a firstdirection and of about 17,000 psi (about 120 KPa) in a second direction(perpendicular to the first direction). The tensile measurements wereperformed at 200 mm/min. load rate with a 1″ (2.5 cm) jaw spacing. Themembrane had a density of about 2.14 g/cm³. The membrane was furthermodified by the application of an FEP coating on one side in accordancewith U.S. Pat. No. 6,159,565, issued to Campbell et al., which isincorporated herein by reference. Next, two wraps of another ePTFE filmmade according to the teachings of Bacino in U.S. Pat. No. 5,476,589 andfurther modified with a discontinuous layer of an FEP material appliedto one side of the ePTFE film were applied to one end of theconstruction (approx. 1″ wide). U.S. Pat. No. 5,476,589 is incorporatedherein by reference. These two wraps had the primary strength directionof the film oriented perpendicular to the mandrel's longitudinal axis.These layers of film provide additional “hoop” or “radial” strength tothe sheath—deployment line construct. The mandrel and sheath—deploymentline construct were placed in an air convection oven obtained from TheGrieve Corporation, Round Lake, Ill., and subjected to a thermaltreatment of 320° C. for 12 minutes. After air cooling, the ePTFE/FEPtube construct was removed from the mandrel and the sacrificial ePTFElayer removed. In this example, a length of sheath—deployment lineextending beyond the end of the stent was provided. The additionallength of sheath—deployment line was folded back over sheath portionenclosing the stent to form a double-walled construct. The double-walledsheath—deployment line had an inner wall and an outer wall. The innerwall was against the stent and the outer wall included the integraldeployment line portion of the construct. The construct was thenattached to a primary catheter shaft using heat and standard materials.

The deployment line portion of the sheath—deployment line was made bysplitting the sheath—deployment line along its length from a proximalend up to, but not including, the sheath portion enclosing the stent.The material thus obtained was gathered into a filament by rolling thematerial. Heat was applied to the material to set the material in thefilamentous form. The deployment line filament was routed through alumen in the primary catheter and connected to a control knob. Thecontrol knob was part of a hub located at the proximal end of theprimary catheter. When the deployment line portion of thesheath—deployment line was pulled, the sheath portion was retracted fromaround the stent.

Example 3

This example describes the incorporation of a means for initiating ormaintaining conversion of the sheath portion of the sheath—deploymentline to deployment line by introducing perforations and intentionalstress risers into the sheath. The sheath—deployment line from Example 2is modified as follows. Prior to rolling the sheath portion into adouble-walled construct and loading the stent therein, the sheath isperforated and/or supplied with “stress risers” that facilitate inseparation of the tubular sheath upon retraction of the deployment lineportion. An appropriate laser for making the perforations or stressrisers is a 20 watt CO₂ laser obtained from Universal Laser Systems,Scottsdale, Ariz. To form the perforations in the sheath portion, thesheath is placed on a sandblasted stainless steel mandrel and exposed tothe laser to cut a series of holes in a part of the tube that willsubsequently serve as the outer wall of the double-walled construct. Thegeometry of the holes can be varied depending on the application. Theperforated sheath portion is used on a deployment line system of thepresent invention as described in Example 2. In this example, tensionapplied to the deployment line portion at the hub end of the catheterresults in retraction of the sheath from around the stent and alsoresults in parting the sheath at the perforations. As the sheath portionis separated, the sheath material becomes convertible to deploymentline.

Example 4

This example describes the incorporation of a means for initiating ormaintaining conversion of the sheath portion of the sheath—deploymentline to deployment line by the use of an appropriate splitting means.

The primary catheter from Example 2 is modified as follows. The primaryportion of the catheter is provided with a notch in the wall in 180degrees opposition and slightly distal to the entry point of thedeployment line portion into the catheter lumen. The notch is furthermodified to provide a small cutting edge in the notch. In oneembodiment, the cutting edge is simply attached to the notch with heat,adhesives, and the like. In another embodiment, the cutting edge isformed by exposing a portion of a metallic braid used to reinforce thecatheter shaft and forming the braid into a cutting edge. In thisexample, tension applied to the deployment line portion at the hub endof the catheter results in retraction of the sheath from around thestent and also results in parting the sheath at the perforations. As thesheath portion is separated, the sheath material becomes convertible todeployment line.

The invention claimed is:
 1. A deployment system for a self-expandingendoluminal device, said deployment system comprising: a catheter havingan elongate body having a proximal end, an opposite distal end, a firstlongitudinal passage having a first longitudinal axis that is coaxialwith the elongate body, and a second longitudinal passage having asecond longitudinal axis that is laterally offset from the firstlongitudinal axis, the first and second longitudinal passages extendinglongitudinally between the proximal and distal ends; a removablethin-film sheath having a sheath portion defining a substantiallyuninterrupted wall that surrounds and constrains at least a portion ofthe endoluminal device toward a delivery profile suitable forendoluminal delivery of the endoluminal device, and a deployment lineportion that is continuous with the sheath portion and extends from thesheath portion and into the second longitudinal passage to facilitateaxial displacement of the thin-film sheath relative to the endoluminaldevice which facilitates expansion of the endoluminal device from thedelivery profile, wherein a combined length of the sheath portion anddeployment line portion as measured along a longitudinal dimension ofthe catheter remains substantially the same both before and afterdeployment of the device.
 2. The deployment system of claim 1, whereinthe sheath portion covering the endoluminal device is shortened and thedeployment line portion is lengthened as the thin-film sheath is axiallydisplaced relative to the endoluminal device during deployment.
 3. Thedeployment system of claim 2, wherein the sheath portion is split as thethin-film sheath is axially displaced relative to the endoluminal deviceduring deployment to facilitate conversion of the split sheath portionto the deployment line portion.
 4. The deployment system of claim 3,including a splitter that splits the sheath portion as the thin-filmsheath is axially displaced relative to the endoluminal device duringdeployment.
 5. The deployment system of claim 4, wherein the splitter isdisposed proximal to the endoluminal device.
 6. The deployment system ofclaim 5, wherein the split sheath portion is gathered and forms afilament that becomes part of the deployment line portion as thethin-film sheath is axially displaced relative to the endoluminal deviceduring deployment.
 7. The deployment system of claim 1, wherein thethin-film sheath comprises a wall with a thickness of less than 0.05 mm.8. The deployment system of claim 1, wherein the thin-film sheathcomprises a continuous film that surrounds the endoluminal device in adouble layered configuration.
 9. The deployment system of claim kwherein one layer of the double layer is placed over the other layer andone layer moves past the other layer upon deployment.
 10. A catheterassembly, said catheter assembly comprising: a catheter having anelongate body having a proximal end, an opposite distal end, a firstlongitudinal passage having a first longitudinal axis that is coaxialwith the elongate body, and a second longitudinal passage having asecond longitudinal axis that is laterally offset from the firstlongitudinal axis, the first and second longitudinal passages extendinglongitudinally between the proximal and distal ends; a self-expandableendoluminal device disposed at or near the distal end of the catheter;and a removable thin-film sheath having a sheath portion defining anuninterrupted wall that surrounds and constrains at least a portion ofthe endoluminal device toward a delivery profile suitable forendoluminal delivery of the endoluminal device, and a deployment lineportion that is continuous with the sheath portion and extends from thesheath portion and into the second longitudinal passage to facilitateaxial displacement of the removable thin-film sheath relative to theendoluminal device which facilitates expansion of the endoluminal devicefrom the delivery profile, wherein the sheath portion converts to thedeployment line portion as the removable thin-film sheath is axiallydisplaced relative to the endoluminal device, wherein a combined lengthof the sheath portion and deployment line portion as measured along alongitudinal dimension of the catheter remains substantially the sameboth before and after deployment of the endoluminal device.
 11. Thedeployment system of claim 10, wherein the sheath portion is split asthe removable thin-film sheath is axially displaced relative to theendoluminal device during deployment to facilitate conversion of thesplit sheath portion to the deployment line portion.
 12. The deploymentsystem of claim 11, including a splitter disposed proximal to theendoluminal device for splitting the removable thin-film sheath portionas the sheath is axially displaced relative to the endoluminal deviceduring deployment.
 13. The deployment system of claim 12, wherein thesheath portion comprises a continuous film that surrounds theendoluminal device in a double layered configuration.
 14. The deploymentsystem of claim 10, wherein the removable thin-film sheath is made of apolymeric material.
 15. The deployment system of claim 14, wherein thepolymeric material includes a fluoropolymer.
 16. The deployment systemof claim 15, wherein the fluoropolymer is polytetrafluoroethylene. 17.The deployment system of claim 16, wherein the polytetrafluoroethyleneis porous expanded polytetrafluoroethylene.
 18. The deployment system ofclaim 17, wherein the porous expanded polytetrafluoroethylene is in theform of a tube.
 19. The deployment system of claim 18, wherein the tubehas a wall with a thickness of less than 0.05 mm.
 20. The deploymentsystem of claim 10, wherein a first portion of the removable thin-filmsheath substantially surrounds at least a portion of the self-expandingendoluminal device and a second portion of the removable thin-filmsheath substantially covers the first portion.
 21. The deployment systemfor a self-expanding endoluminal device of claim 20, wherein thedeployment line is integral with the second portion of the removablethin-film sheath.
 22. A deployment system for a self-expandingendoluminal device, said deployment system comprising: a catheter havingan elongate body having a proximal end, an opposite distal end, a firstlongitudinal passage having a first longitudinal axis that is coaxialwith the elongate body, and a second longitudinal passage having asecond longitudinal axis that is laterally offset from the firstlongitudinal axis, the first and second longitudinal passages extendinglongitudinally between the proximal and distal ends; a splitter disposedproximal the endoluminal device that splits the sheath portion as thethin-film sheath is axially displaced relative to the endoluminal deviceduring deployment; and a removable thin-film sheath having a sheathportion defining a substantially uninterrupted wall that surrounds andconstrains at least a portion of the endoluminal device toward adelivery profile suitable for endoluminal delivery of the endoluminaldevice, and a deployment line portion that is continuous with the sheathportion and extends from the sheath portion and into the secondlongitudinal passage to facilitate axial displacement of the thin-filmsheath relative to the endoluminal device which facilitates expansion ofthe endoluminal device from the delivery profile, wherein the sheathportion covering the endoluminal device is shortened and the deploymentline portion is lengthened as the thin-film sheath is axially displaced,a combined length of the sheath portion and deployment line portion asmeasured along a longitudinal dimension of the catheter remainingsubstantially the same both before and after deployment of theendoluminal device, and wherein the sheath portion is split and gatheredto form a filament that becomes part of the deployment line portion asthe thin-film sheath is axially displaced relative to the endoluminaldevice during deployment to facilitate conversion of the split sheathportion to the deployment line portion.